[PATCH] staging: iio: frequency: ad9834: Validate frequency parameter value

[Aleksandr Mishin <amishin@t-argos.ru>]

In ad9834_write_frequency() clk_get_rate() can return 0. In such case
ad9834_calc_freqreg() call will lead to division by zero. Checking
'if (fout > (clk_freq / 2))' doesn't protect in case of 'fout' is 0.
ad9834_write_frequency() is called from ad9834_write(), where fout is
taken from text buffer, which can contain any value.

Modify parameters checking.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 12b9d5bf76bf ("Staging: IIO: DDS: AD9833 / AD9834 driver")
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
---
 drivers/staging/iio/frequency/ad9834.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c
index a7a5cdcc6590..9e42129f44f7 100644
--- a/drivers/staging/iio/frequency/ad9834.c
+++ b/drivers/staging/iio/frequency/ad9834.c
@@ -114,7 +114,7 @@ static int ad9834_write_frequency(struct ad9834_state *st,
 
 	clk_freq = clk_get_rate(st->mclk);
 
-	if (fout > (clk_freq / 2))
+	if (!fout || fout > (clk_freq / 2))
 		return -EINVAL;
 
 	regval = ad9834_calc_freqreg(clk_freq, fout);
-- 
2.30.2